From Bushwalk Australia
A deck built on or near a bushwalking track for the purpose of pitching one or more tents upon. Not only does it provide an easy, flat an clean place to pitch a tent, but they avoid having other nearby areas degraded by over use along popular tracks.
In Tasmania, these are usually raised off the ground, and constructed of treated pine (1). However, there are a few made of rubber mats embedded into gravel (3) in the ground, such that tent pegs can still be used in the gravel/soil.
The wooden variety usually have a series of nails, hooks, clips and/or ropes/cables to be used for attaching tents (4), instead of using tent pegs. Where ropes or cables are used, these are suited to longitudinally tensioned tents (most modern tunnel tents) better than tents which require fixed anchor points, as it can be difficult to get the end of the ropes/cables in precisely the right locations for each anchor point, however, nails between the decking boards, usually help with this. Some also have a small stainless steel plate that can be used as a "home" for your cooker. This prevents you burning down the deck!
In most locations in Tasmania where tent platforms have been built, they are usually large enough to accommodate two medium sized tents each, and are built in groups with each platform having a little distance, and privacy, from the others. However, they do vary somewhat in size and configuration (2, 5).
Note that a large square wooden deck out in the open, not near any other tent platforms, is most likely a helicopter landing pad. Do not camp on a heli-pad unless official signs say that this is permitted (some heli-pads permit camping only between dusk and dawn, others do not permit camping at all).